Third-order nonlinear optical response of ion-implanted embedded arrays of plasmonic gold nanoparticles

Abstract Arrays of plasmonic gold nanoparticles, embedded in fused silica plates, were prepared by implanting 2 MeV Au+ ions through a silica particle lithographic mask. The nonlinear optical response of these periodic arrays was experimentally investigated using the z-scan technique at 532 nm with 26 ps pulses from a Nd:YAG laser. The open-aperture z-scan measurements were performed following different linear polarization angles for the incident light beam. A strong saturable absorption and a very clear nonlinear dichroic behavior were determined, the latter indicated by a sinusoidal modulation of the nonlinear absorption coefficient β (up to about 20% of its absolute value) as a function of the polarization angle. This result gives clear evidence of the formation of ordered arrays of embedded Au nanoparticles, corresponding to a honeycomb lattice symmetry with a modulation period of 30°.